the examination of surface chem istry and porosity of carbon ...ants and the application of remedial...

743

†To whom correspondence should be addressed.

E-mail: [email protected]

Korean J. Chem. Eng., 29(6), 743-749 (2012)DOI: 10.1007/s11814-011-0237-8

INVITED REVIEW PAPER

The examination of surface chemistry and porosity of carbon nanostructured adsorbents for 1-naphthol removal from petrochemical wastewater streams

Mansoor Anbia† and Seyyed Ershad Moradi

Research Laboratory of Nanoporous Materials, Faculty of Chemistry,Iran University of Science and Technology, Narmak, Tehran 16846, Iran

(Received 6 June 2011 • accepted 9 September 2011)

Abstract−Chemically modified mesoporous carbon (CMMC) and chemically modified activated carbon (CMAC)

were prepared by an acid surface modification method from mesoporous carbon (MC) and commercial activated carbon

(AC) by wet impregnation method. The structural order and textural properties of the nanoporous materials were studied

by XRD and nitrogen adsorption. The presence of carboxylic functional groups on the carbon surface was confirmed

by FTIR analyses. Adsorption of 1-naphthol over various porous adsorbents such as CMMC, CMAC, MC and AC

was studied. The adsorption isotherms of 1-naphthol were in agreement with a Langmuir model; moreover, the uptake

capacity of 1-naphthol followed the order: CMMC>MC>CMAC>AC.

Key words: 1-Naphthol, Chemical Modification, Activated Carbon, Adsorption, Langmuir Isotherm, Nanoporous

INTRODUCTION

Polycyclic aromatic hydrocarbons (PAHs), which are chemical

species with two to six fused benzene rings, are well known toxic

hazardous pollutants and highly potent carcinogens that can cause

tumors in some organisms [1]. In recent years, PAHs contamina-

tion in water systems has drawn increasing attention. PAHs origi-

nate from natural and anthropogenic sources that include engine

exhaust, industrial processes, crude oil, urban run-off, domestic heat-

ing systems, incinerators and smoke. Natural sources include ter-

restrial coal deposits, volcanic eruptions and forest fires. The main

sources of PAHs in surface water are atmospheric deposition, runoff

from contaminated soils and deposition from sewage discharges [2].

Most PAHs are hydrophobic with high boiling and melting points

and electrochemical stability. Therefore, they can exist and be accu-

mulated in soils or water for a long time [3].

Adsorption treatment provides a simple and universal approach

to effectively removing organic pollutants from the aquatic envi-

ronment. The removal of toxic organic pollutants from water is a

problem, particularly when they are present in low concentrations.

Several studies have focused on the fate and transport of these pollut-

ants and the application of remedial technologies to manage them

[4-10]. Activated carbons present an outstanding adsorption capac-

ity that stems from their high surface area, pore structure and surface

chemical properties. These materials are effective adsorbents for

priority pollutants, therefore being suitable for the decontamination

of water and wastewater. These porous carbons are generally mi-

croporous, and the preparation of carbon materials with well ordered

mesoporous structure would offer many application possibilities

not only in the adsorption and separation of large molecules whose

molecular sizes are too large to enter micropores but also in electri-

cal double layer capacitors, gas separation, catalysis, water and air

purification and energy storage. Recently, Ryoo et al. prepared or-

dered mesoporous carbons from mesoporous silica templates such

as MCM-48, SBA-1 and SBA-15 using sucrose as the carbon source

[11-14].

Adsorption plays an important role in these processes. There-

fore, the interactions of such compounds with the mesoporous car-

bon surface must be studied in detail. The mesoporous carbon materi-

als adsorption capacity depends on quite different factors. Obviously,

it depends on the mesoporous carbon’s characteristics: texture (sur-

face area, pore size distributions), surface chemistry (surface func-

tional groups) [15-17]. It also depends on adsorptive characteris-

tics: molecular weight, polarity, pKa, molecular size, and functional

groups. The influence of the texture and surface chemistry of nan-

oporous carbons in the adsorption of organic compounds has been

studied for years, and many references on this topic can be found

in the literature. The adsorption of organic molecules from aque-

ous solutions on nanoporous carbons has been recently reviewed

[18,19], and it was shown that the specific mechanism by which

the adsorption of many organic compounds takes place on this ad-

sorbent is still ambiguous. Since the pioneering works of Coughlin

and Ezra [20] and Mattson et al. [21] to others published more re-

cently [22-25], it was found that the adsorption capacity is signifi-

cantly affected by the carbonaceous adsorbent surface chemistry.

Different studies have been done on the interaction between acid

oxygen-containing surface groups and the adsorption of organic com-

pounds in aqueous solution. There are two types of interactions be-

tween the adsorbate and the carbonaceous adsorbent: electrostatic

and dispersive [17-19]. The former appears when the adsorptive is

dissociated under the experimental conditions used; for the latter,

three mechanisms are proposed: π-π dispersion interaction mecha-

nism, the hydrogen bonding formation mechanism, and the electron

donor-acceptor complex mechanism. The π-π dispersion interac-

tion mechanism is the most widely accepted [17,18]. The surface

chemistry and solution pH are the most important factors control-

ling the adsorption process [26]. Most of the aromatic pollutants

744 M. Anbia and S. E. Moradi

June, 2012

are found in water solution in the molecular state for a broad range

of pH values. In this case, dispersive interactions are predominant,

mainly because of the attraction between the π orbitals on the car-

bon basal planes and the electronic density in the adsorbate aro-

matic rings (π-π interactions). However, when the solution pH is

very high or very low, ions may be present, so electrostatic interac-

tion between them and charged functional groups on the carbon

surface could be significant [17].

In this work, the influence of the texture and surface chemistry

of nanoporous carbon adsorbent were systematically studied in the

adsorption of 1-naphthol (NA). For this purpose, mesoporous car-

bon and commercial activated carbon with quite different textural

properties were selected in order to analyze the influence of the tex-

tural parameters. Then both of them were modified by selected oxi-

dative treatments, producing samples differing in the surface chem-

istry and textural parameters, to study their influence in the adsorp-

tion process. Interestingly, it has been found that the adsorption cap-

ability of chemically modified mesoporous carbon for 1-naphthol

is much higher compared to that of other adsorbents. Langmuir and

Freundlich adsorption isotherms were studied to explain the sorp-

tion mechanism.

EXPERIMENTAL

1. Materials

The reactants used in this study were synthesized mesoporous

silica (MCM-48) and sucrose as a carbon source, sulfuric acid as a

catalyst for synthesis of mesoporous carbon and nitric acid as a oxi-

dizer agent, 1-naphthol and commercial activated carbon. All the

chemicals were of analytical grade and purchased from Merck.

2. Synthesis of Mesoporous Carbon (MC)

High-quality MCM-48 sample was prepared following the syn-

thesis procedure reported by Shao et al. [27]. Then 1.25 g sucrose

and 0.14 g H2SO4 in 5.0 g H2O were dissolved, and this solution

was added to 1 g MCM-48. The sucrose solution corresponded ap-

proximately to the maximum amount of sucrose and sulfuric acid

that could be contained in the pores of 1 g MCM-48. The resultant

mixture was dried in an oven at 373 K, and subsequently, the oven

temperature was increased to 433 K. After 6 h at 433 K, the MCM-

48 silica containing the partially carbonizing organic masses was

added to an aqueous solution consisting of 0.75 g sucrose, 0.08 g

H2SO4 and 5.0 g H2O. The resultant mixture was dried again at 373

K, and subsequently the oven temperature was increased to 433 K.

The sample turned very dark brown or nearly black. This powder

sample was heated to 1,173 K under vacuum using a fused quartz

reactor equipped with a fritted disk. The carbon-silica composite

thus obtained was washed with 1 M NaOH solution of 50% etha-

nol-50% H2O twice at 363 K, in order to dissolve the silica tem-

plate completely. The carbon samples obtained after the silica removal

were filtered, washed with ethanol and dried at 393 K.

3. Chemical Modification of MC and Commercial Activated

Carbon

To introduce oxygen-containing functional groups on the carbon

surface, MC (or commercial activated carbon) was oxidized by nitric

acid under optimal modification condition, such as nitric acid con-

centration, oxidation temperature [28]. 0.1 g of dried MC (or com-

mercial activated carbon) powder was treated with 15 ml of HNO3

solution (2 M solution) for 1 h in the 80 oC under refluxing. After

oxidation, samples were recovered and washed thoroughly with

distilled water until the pH was close to 7.

4. Characterization

The X-ray powder diffraction patterns were recorded on a Phil-

ips 1830 diffractometer using Cu Kα radiation. The diffractograms

were recorded in the 2θ range of 0.8-10 with a 2θ step size of 0.01o

and a step time of 1 s. Adsorption-desorption isotherms of the syn-

thesized samples were measured at 77 K on Micromeritics model

ASAP 2010 sorptometer to determine an average pore diameter.

Pore-size distributions were calculated by the Barrett-Joyner-Hal-

enda (BJH) method, while surface area of the sample was meas-

ured by Brunauer-Emmet-Teller (BET) method. The Fourier trans-

form infrared spectra for the unmodified and modified samples were

measured on a DIGILAB FTS 7000 instrument under attenuated

total reflection (ATR) mode using a diamond module.

5. Adsorption Studies

A stock solution of 50 ppm for 1-naphthol (NA) was prepared

by dissolving an appropriate amount of the 1-naphthol in ultra-pure

water (18 MΩ cm) derived from a Milli-Q plus 185 water purifier.

Batch adsorption isotherms were performed by shaking 500 ml amber

Winchester bottles containing the required concentration of the 1-

naphthol in a Gallenkamp incubator shaker. The shaker was set at

a temperature of 298±1 K and a speed of 200 rpm. Initial solution

concentration of 0-0.14 mmol/L was prepared by pipetting out the

required amounts of the 1-naphthol from the stock solution. The

volume of solution in each bottle was maintained at 500 mL and

the solutions were adjusted to pH 5. About 5 mg of each adsorbent

was weighed accurately on aluminum foils using a Sartorious (Model

BP 201D) analytical balance. The adsorbents were transferred care-

fully into the bottles using 10 mL solutions from the bottles. The

bottles were shaken vigorously before shaking for different time in

the incubator shaker (New Brunswick Scientific C25 Model).

The amount of 1-naphthol adsorbed was calculated by subtract-

ing the amount found in the supernatant liquid after adsorption from

the amount of 1-naphthol present before addition of the adsorbent

by UV-Vis spectrophotometer (UV mini 1240 Shimadzu). Absor-

bance was measured at wavelength (λmax

) 331 nm for determination

of 1-naphthol content. Calibration experiments were done separately

before each set of measurements with 1-naphthol’s solution of dif-

ferent concentrations. Centrifugation prior to the analysis was used

to avoid potential interference from suspended scattering particles

in the UV-Vis analysis.

The adsorption capacities were calculated based on the differ-

ences of the concentrations of solutes before and after the experi-

ment according to Eq. (1) [29].

(1)

Where qe is the concentration of the adsorbed solute (mmol/g); C

o

and Ce are the initial and final (equilibrium) concentrations of the

solute in solution (mmol/L); V (mL) is the volume of the solution

and W (g) is the mass of the adsorbent.

6. Adsorption Kinetics of 1-Naphthol (NA)

(2)

qe =

Co − Ce( )V

W-------------------------

qt =

Co − Ct( )V

W------------------------

The examination of surface chemistry and porosity of carbon nanostructured adsorbents for 1-naphthol removal from …… 745

Korean J. Chem. Eng.(Vol. 29, No. 6)

For the measurement of the time resolved uptake of 1-naphthol onto

adsorbents, 15 ml of distilled water was mixed with 60 mg of MC

(or activated carbon) in a 500 ml flask for about 10 min. 285 ml of

1-naphthol solution was quickly introduced into the flask (keeping

the initial concentrations of the resulting solutions at 50 ppm) and

stirred continuously at 20 oC. Samplings were done by fast filtration

at different time intervals. The concentration of residual 1-naphthol

in the solution was determined and the adsorption amount qt was

calculated according to Eq. (2).

Where qt is the adsorption amount at time t, C

o is the initial con-

centration of 1-naphthol solution, Ct is the concentration of 1-naph-

thol solution at time t, and V is the volume of 1-naphthol solution

and m is the mass of carbonaceous adsorbent.

RESULTS AND DISCUSSION

1. Characterization of the CMMC and MC Samples

The quality of the mesoporous carbon samples prepared in this

study was examined by nitrogen adsorption-desorption analysis and

X-ray diffraction (XRD) techniques.

Nitrogen physisorption is the method of choice to gain knowl-

edge about mesoporous materials. This method gives information

on the specific surface area and the pore diameter. Calculating pore

diameters of mesoporous materials using the BJH method is com-

mon. Former studies show that the application of the BJH theory

gives appropriate qualitative results, which allow a direct compari-

son of relative changes between different mesoporous materials.

The nitrogen sorption isotherms of the MC and CMMC have

the typical type IV shape. Interestingly, the pore size distributions

are essentially the same as before acid oxidation. The adsorption

uptakes at relative pressure close to p/po=0 are identical (p the equi-

librium pressureare and po the saturation pressure of adsorbents at

Table 1. Textural parameters of the MC and CMMC employedin this study

Adsorbent d spacing (nm) ABET (m2 g−1) Vp (cm3 g−1)

MC 3.4 1010.5 0.69

CMMC 3.1 0985.4 0.62

Fig. 1. Adsorption-desorption isotherms of nitrogen at 77 K on MCand CMMC. The insert shows the BJH pore size distribu-tion calculated from the desorption branch of the isotherm. Fig. 3. FT-IR spectra of MC and CMMC samples.

Fig. 2. XRD pattern of CMMC and MC.

the temperature of adsorption). However, the total uptakes are slightly

different, decreasing with the surface modification with acid. As

shown in Table 1, the decreases in the specific surface areas and

pore volumes are 2.5% and 9.5%, respectively. From the nitrogen

sorption isotherms (Fig. 1) of mesoporous carbon type carbons before

and after acid oxidation, it can be seen that after oxidation the ob-

tained carbons still have type IV isotherms, indicating that mesopo-

rosity is still preserved. However, the oxidation leads to a decrease

in the total uptake of the oxidized carbons, which reflects the de-

crease of the total pore volume resulting from acid oxidation. Inter-

estingly, the oxidized carbons essentially keep the bimodal pore size

distribution, which is characteristic of the parent MC. The textural

parameters listed in Table 1 clearly confirm the structural changes of

oxidized MC. Especially, the variations of the surface area and pore

volume are significant with the increase in the acid concentration.

To check the structural degradation, XRD data of CMMC and

MC were obtained on Philips 1830 diffractometer using Cu Kα ra-

diation of wavelength 0.154 nm. Fig. 2 shows the XRD peaks of

the samples. The XRD patterns of CMMC showed three diffrac-

tion peaks that can be indexed to (110), (210), and (220) in the 2θ

range from 0.8o to 10o, representing well-ordered cubic pores [11].


June, 2012

The XRD patterns of MC carbon and CMMC (in Fig. 2) show well-

resolved reflections indicating that MC carbon nicely maintains it

original structure even after the oxidization with 2 M nitric acid.

For CMMC sample, the cubic structure of MC was maintained well,

but the XRD reflections become less pronounced, which might be

due to the partial damage of the mesoporous (cubic) structure or

due to the decreased contrast between walls and pores because of

the cleavage of the carbon species from the pore walls.

The FT-IR technique was used to monitor changes on the sur-

face of the mesoporous carbon and the content of the introduced

oxygen-containing functional surface group [6,7]. Fig. 3 shows the

FT-IR spectra of MC and as treated CMMC samples. A broad band

at around 3,450 cm−1 was observed in all samples. The O-H stretch-

ing vibration of the adsorbed water molecules, which also had a

bending vibration mode corresponding to the band recorded at 1,630

cm−1, mainly caused it. Bands at 1,643-1,750 cm−1 denoted the ab-

sorption of stretching and bending vibration modes of -COOH on

the surface of mesoporous carbon materials (indicated by arrow).

In addition, the stretching vibration of C-O bonds caused the broad

band that appeared at 1,100 cm−1. The relative intensity of these bands

in CMMC samples was higher than those of the MC sample, indicat-

ing that more oxygen-containing functional groups were introduced

when the oxidation was done. This fact, that oxidation caused higher

content of functional groups, indicated that there were chemical reac-

tions on the carbon surface between the nitric acid and C atoms,

which were partially oxidized to form C-OH and/or -COOH. The

reaction equations were proposed as follows:

-C-oxidize-C-OH

-C-oxidize-C-OOH

2. Characterization of the CMAC and AC Samples

The nitrogen adsorption isotherms of activated carbon samples

are shown in Fig. 4. The N2 adsorption isotherms are all type I even

though their shape varies significantly, indicative of microporous

carbons. Some previous works for different activated carbons [30-

33] have observed similar isotherms. The adsorption isotherm of

CMAC is typical for highly microporous carbon, with a very steep

initial uptake and a relative absence of meso- and macroporosity;

however, sample AC reached adsorption saturation at lower P/Po.

Fig. 4. Adsorption-desorption isotherms of nitrogen at 77 K on ACand CMAC.

Table 2. Textural parameters of the AC and CMAC employed inthis study

Adsorbent d Spacing (nm) ABET (m2 g−1) Vp (cm3 g−1)

AC 2.16 0936 0.41

CMAC 2.09 1209 0.59

Fig. 5. XRD analysis of the activated carbons and chemical modi-fied activated carbon.

Fig. 6. FT-IR spectra of AC and CMAC samples.

In addition, the adsorption ability of CMAC is higher than AC ac-

cording to the higher position of isotherm curve, as shown in Fig. 4.

Some porous structure parameters of the activated carbons are shown

in Table 2. The results show that chemical modification prior to acti-

vation dramatically increased the BET surface area and total pore

volume Vt (estimated from the liquid volume of nitrogen adsorbed

at relative pressure P/P0=0.996) of the resulting activated carbon. This

is a result of more ‘active site’ by the formation of oxygen groups,

which makes it easier for acid to react with the carbon of the pre-

cursor, and finally developed the porous structure.

The XRD analysis was carried out on powder samples to inves-

tigate the structural changes. The typical XRD patterns of the acti-

vated carbons and their precursors are shown in Fig. 5. As shown

in Fig. 5, the XRD result is not very clear, but something, which is

very important, is the overall changes in XRD result. It can be clearly

seen that there are diffraction peaks around 2θ=250 for AC, corre-



sponding to the diffraction of (002). The (002) peak of AC is broader

and the (002) peak of CMAC disappeared.

In the FTIR spectra (Fig. 6) of the AC and CMAC tested, the band

of O-H stretching vibrations (3,600-3,100 cm−1) was due to surface

hydroxylic groups and chemisorbed water. The asymmetry of this

band at lower wave numbers indicates the presence of strong hy-

drogen bonds. Below 2,000 cm−1, the FTIR spectra of activated car-

bon (AC) exhibit absorption typical of surface functional groups

and component oxygen species of the structural network. These

spectra are similar to those reported of other carbons derived from

a wide variety of sources [34-37]. The presence of bands at 1,750

cm−1 and 1,630 cm−1 can be, respectively, attributed to the stretch-

ing vibrations of C=O moieties in carboxylic or ester and quinine

structures [36]. Since H2O is sorbed on the surface of OH bending

vibrations can also describe activated carbons with the participation

of specific (hydrogen bonds, chemisorptions due to surface oxide

hydration) and non-specific interactions (physical adsorption), the

bands in the 1,500-1,600 cm−1 region. The complicated nature of

the adsorption bands in the 1,650-1,500 cm−1 region suggests that

aromatic ring bands and double bond (C=C) vibrations overlap the

aforementioned C=O stretching vibration bands and OH deforma-

tion bands [36]. After oxidation, the band characteristic of carbonyl

moieties in a carboxylic acid (1,750-1,700 cm−1) increases and there

is a simultaneous, considerable increase in band intensity of these

carbonyl functional groups in different surroundings. This suggests

an increase in the number of ether and hydroxylic structures in the

carbon investigated.

3. Adsorption Studies

3-1. Effect of Agitation Speed

The effect of agitation speed on removal efficiency of 1-naph-

thol on carbonaceous adsorbents was studied by varying the speed

of agitation from 50 to 250 rpm, while keeping the analyte concen-

tration, contact time, pH, temperature and dose of the adsorbent as

constant. As it is demonstrated in Fig. 7, the 1-naphthol removal

efficient generally increased with increasing agitation speed from

50 rpm to 150 rpm and the adsorption capacity of all adsorbents

remained constant for agitation rates greater than 150 rpm. These

results can be associated with the fact that the increase of the agitation

speed improves the diffusion of analyte into the pores of the ad-

sorbents. This also indicates that a shaking rate in the range 150-

200 rpm is sufficient to assure that the maximum available sites of

adsorbent existing in the pores of adsorbents are made readily avail-

able for 1-naphthol uptakes. For convenience, agitation speed of

150 rpm was selected as the optimum speed for all the adsorption

experiments.

3-2. Effect of Contact Time and Concentration

To establish equilibration time for maximum uptake and to know

the kinetics of adsorption process, the adsorption of 1-naphthol on

carbonaceous adsorbent was studied as a function of contact time,

and results are shown in Fig. 8. It is seen that the rate of uptake of

the 1-naphthol is rapid in the beginning and 50% adsorption is com-

pleted within 80 min. Fig. 8 also indicates that the time required for

equilibrium adsorption is 200 min. Thus, for all equilibrium adsorp-

tion studies, the equilibration period was kept 240 min. The effect

of concentration on the equilibration time was also investigated as

a function of initial 1-naphthol concentration, and the results are

shown in Fig. 9 (on MC). It was found that time of equilibrium as

well as time required to achieve a definite fraction of equilibrium

adsorption is independent of initial concentration. These results indi-

cate that the adsorption process is first order.

3-3. Effect of Chemical Modification

To evaluate the efficacy of the prepared adsorbents, the equilib-

Fig. 7. Effect of agitation speed on the adsorption capacity of ad-sorbents (adsorbents dosage=0.2 g/L, [NA]=50 ppm, con-tact time=4 h, T=298 K and pH=7).

Fig. 9. Effect of initial concentration on removal of 1-naphthol (con-tact time=4 h, agitation speed=150 (rpm), adsorbent dos-age=0.2 g/L, T=298 K and pH=7).

Fig. 8. Effect of contact time on removal of 1-naphthol ([NA]=50mg/L, agitation speed=150 (rpm), adsorbent dosage=0.2 g/L, T=298 K and pH=7).


June, 2012

rium adsorption of the 1-naphthol was studied as a function of equi-

librium concentration. The adsorption isotherms of 1-naphthol on

adsorbents are shown in Fig. 10. It is seen that the order of adsorp-

tion in terms of amount adsorbed (mmol/g) on different adsorbents

is CMMC>MC and CMAC>AC. The higher adsorption capacity

of CMMC and CMAC can be explained by several facts. Undoubt-

edly, increasing in interaction as a cause of more functional group

in CMMC and CMAC explained this. It is also surmised that the

anchoring ability of -COOH groups located inside and at the entrance

of the mesopores might obstruct desorption of PAHs molecules from

the pore channels of chemically oxidized mesoporous carbon, result-

ing in an increase in the PAHs adsorption capacity.

3-4. Langmuir and Freundlich Isotherms

To indicate the sorption behavior and to estimate of adsorption

capacity, adsorption isotherms have been studied. The adsorption

processes of 1-naphthol were tested with Langmuir and Freundlich

isotherm models [38]. Two commonly used empirical adsorption

models, Freundlich and Langmuir, which correspond to heteroge-

neous and homogeneous adsorbent surfaces, respectively, were em-

ployed in this study. The Freundlich model is given by Eq. (3):

(3)

where Kf and n are the Freundlich constants related to adsorption

capacity and intensity, respectively. In the second model, the Lang-

muir equation assumes maximum adsorption occurs when the sur-

face is covered by the adsorbate, because the number of identical

sites on the surface is finite. Eq. (4) (Langmuir equation) is given

as follows:

(4)

where qe (mmol g−1) is the amount adsorbed at equilibrium concen-

tration Ce (mmol L−1), qm (mg g−1) is the Langmuir constant repre-

senting maximum monolayer capacity and b is the Langmuir con-

stant related to energy of adsorption.

The isotherm data have been linearized using the Langmuir equa-

tion and Freundlich equation. The regression constants are in Table 3.

The value of the correlation coefficients shows that the data con-

form well to the Langmuir equation.

CONCLUSIONS

Liquid-phase oxidation by nitric acid was used for the surface

modification of carbon nanoporous materials. The chemically mod-

ified nanoporous carbon prepared in this work is suitable for the

adsorption of aqueous 1-naphthol from industrial wastewater. It is

indicated that the surface oxygen groups of the precursor could act

as ‘active site’, which plays an important role in adsorption process.

The adsorption behavior of 1-naphthol on the carbonaceous adsor-

bent from aqueous solution has been investigated. All adsorption

isotherms were fitted well by Langmuir model.

ACKNOWLEDGEMENTS

The Research Council of Iran University of Science and Tech-

nology and Iranian Nanotechnology Initiative Council are acknowl-

edged for the financial support.

REFERENCES

1. R. G. Harvey, Polycyclic Aromatic Hydrocarbons, Chemistry and

Carcinogenicity, Cambridge University Press, Cambridge, England

(1991).

2. D. M. Wassenberg and R. T. Di Giulio, Environ. Health Perspect.,

17, 1658 (2004).

3. C. Chang, C. Y. Chang, K. Chen, W. Tsai, J. Shie and Y. Chen, J.

Colloid Interface Sci., 277, 29 (2004).

4. M. Anbia, M. K. Rofouei and S. W. Husain, Chin. J. Chem., 24, 1026

(2006).

5. M. Anbia, M. K Rofouei and S. W. Husain, Oriental J. Chem., 21,

199 (2005).

6. M. Anbia and S. E. Moradi, Chem. Eng. J., 148, 452 (2008).

7. M. Anbia and S. E. Moradi, Appl. Surf. Sci., 5041, 255 (2009).

8. M. Hudson, S. W. Husain and M. Anbia, J. Ir. Chem. Soc., 2, 54

Lnqe = Kf + 1

n---⎝ ⎠⎛ ⎞ Celnln

Ce

qe

----- = 1

qmb--------⎝ ⎠⎛ ⎞

+ 1

qm

-----⎝ ⎠⎛ ⎞Ce

Fig. 10. Adsorption isotherm for 1-naphthol removal on carbon-aceous adsorbents (contact time=4 h, agitation speed=150(rpm), adsorbent dosage=0.2 g/L, T=298 K and pH=7).

Table 3. Langmuir and Freundlich constants for adsorption of PAHs on CMMC and CMAC

Langmuir Freundlich

Adsorbent qm (mmol/g) b (L/mmol) R2 KF (mmol/g) n (L/mmol) R2

CMMC 3.0 47.14 0.999 5.8 2.75 0.964

MC 1.7 27.85 0.999 4.0 2.00 0.961

CMAC 0.9 49.26 0.996 1.6 2.85 0.937

AC 0.5 30.70 0.983 1.1 2.29 0.971



(2005).

9. N. Tancredi, N. Medero, F. Moller, J. Piriz, C. Plada and T. Cordero,

J. Colloid Interface Sci., 279, 357 (2004).

10. Y. Lin and H. Teng, Carbon, 41, 2865 (2003).

11. S. Jun, S. H. Joo, R. Ryoo, M. Kruk, M. Jaroniec, Z. Liu, T. Ohsuna

and O. Terasaki, J. Am. Chem. Soc., 122, 10712 (2000).

12. R. Ryoo, S. H. Joo and S. Jun, J. Phys. Chem. B., 103, 7743 (1999).

13. R. Ryoo, S. H. Joo, M. Kruk and M. Jaroniec, Adv. Mater., 13, 677

(2001).

14. S. H. Joo, S. J. Choi, I. Oh, J. Kwak, Z. Liu, O. Terasaki and R. Ryoo,

Nature, 412, 169 (2001).

15. R. C. Bansal, J. Donnet and H. F. Stoeckli, Active Carbon, Dekker,

New York (1988).

16. S. J. Gregg and K. S. W. Sing, Adsorption, Surface Area and Poros-

ity, Academic Press, London (1982).

17. L. R. Radovic, I. F. Silva, J. I. Ume, J. A. Menéndez, C. A. Leon

and A. W. Scaroni, Carbon, 35, 1339 (1997).

18. L. R. Radovic, C. Moreno-Castilla and J. Rivera-Utrilla, in: L. R.

Radovic (Ed.), Chemistry and Physics of Carbon, Dekker, New

York, 27 (2000).

19. C. Moreno-Castilla, Carbon, 42, 83 (2004).

20. R. Coughlin and F. S. Ezra, Environ. Sci. Technol., 2, 291 (1968).

21. J. S. Mattson, J. H. B. Mark, M. D. Malbin, J. W. J. Weber and J. C.

Crittenden, J. Colloid Interface Sci., 31, 116 (1969).

22. L. Li, P. A. Quinlivan and D. R. U. Knappe, Carbon, 40, 2085

(2002).

23. M. Franz, H. A. Arafat and N. G. Pinto, Carbon, 38, 1807 (2000).

24. S. Haydar, M. A. Ferro-Garcia, J. Rivera-Utrilla and J. P. Joly, Car-

bon, 41, 387 (2003).

25. P. Pendleton, S. H. Wong, R. Schumann, G. Levay, R. Denoyel and

J. Rouquerol, Carbon, 35, 1141 (1997).

26. C. Moreno-Castilla, J. Rivera-Utrilla, M. V. López-Ramón and F.

Carrasco-Marín, Carbon, 33, 845 (1995).

27. Y. Shao, L. Wang, J. Zhang and M. Anpo, Micropor. Mesopor.

Mater., 109, 20835 (2005).

28. P. A. Bazul⁄a, A. H. Lu, J. J. Nitz and F. Schüth, Micropor. Mesopor.

Mater., 108, 266 (2008).

29. R. Crisafully, M. A. Milhome, R. M. Cavalcante, E. R. Silveira, D.

Keukeleire and F. Nascimento, Bioresour. Technol., 99, 4515 (2008).

30. Y. Xun, Z. Shu-Ping, X. Wei, C. Hong-You, D. Xiao-Dong, L. Xin-

Mei and Y. Zi-Feng, J. Colloid Interface Sci., 310, 83 (2007).

31. D. Savova, N. Petrov, M. F. Yardim, E. Ekinci, T. Budinova, M. Raz-

vigorova and V. Minkova, Carbon, 41, 1897 (2003).

32. A. Celzard, A. Perrin, A. Albiniak, E. Broniek and J. F. Mareche,

Fuel, 86, 287 (2007).

33. C. S. Azevedo Diana, J. C. S. Araujo, Bastos-Neto Moises, B. Torres,

F. Jaguaribe and L. Cavalante, Micropor. Mesopor. Mater., 100, 361

(2007).

34. S. Biniak, G. Szymanski, J. Siedlewski and A. Swiatkoski, Carbon,

35, 1799 (1997).

35. B. Stohr, H. P. Boehm and R. Schlogl, Carbon, 29, 707 (1991).

36. P. E. Fanning and M. A. Vannice, Carbon, 31, 721 (1993).

37. V. Gómez-Serrano, M. Acedo-Ramos, A. J. Lopez-Peinado and C.

Valenzuela-Calahorro, Fuel, 73, 387 (1994).

38. C. Moreno-Castilla, F. Carrasco-Marin, F. J. Maldonado-Hódar and

J. Rivera-Utrilla, Carbon, 36, 145 (1998).

the examination of surface chem istry and porosity of carbon ...ants and the application of remedial...

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